What marks us, and how do we react to our impressions, both large and small, of life? These are the questions asked by San Francisco author Michelle Richmond in her wonderful second novel, "The Year of the Fog."

Despite all its drama -- and this heart-wrenching tale does ratchet up the tension -- this is primarily a story of echoes and repercussions. For the first two-thirds of this spare, moving book, very little actually happens. Before the book opens, Abby, the narrating protagonist, takes her fiance's 6-year-old daughter, Emma, to the beach. Emma struggles to run ahead, and, although it's a foggy day, Abby lets her. She then takes her eyes off the little girl for the minute, maybe three minutes, necessary to photograph a dead seal pup washed up on the shore, and suddenly Emma is gone.

As the story opens, Abby is already replaying those few lost moments in her mind. Interspersed with the actual search for the girl, who may have drowned or been kidnapped, are her asides about photography -- which she interprets as the art of capturing impressions -- and the elusive quality of memory. Over and over she asks herself what she has missed, how she could have let the girl go and what really happened to the child in the blue canvas shoes, a little girl with a big personality who hated the water and loved applesauce.

Most of this book stays right there, the fog of the beach transformed into a metaphor for the bereaved couple's state of mind. Although Abby and her shell-shocked fiance, Jake, count the days, minutes and seconds since Emma disappeared, they are essentially beyond time, trapped in the moment of their loss. As the investigation takes on a momentum of its own, each reacts according to personal nature, abandoning any semblance of normalcy in the process. Jake's a teacher, a planner, and he throws himself into organizing a storefront volunteer group that keeps him frenetically busy. Abby, a loner, takes off on her own, spending long hours at the beach and in increasingly unsavory neighborhoods, searching for some sign of the girl and scouring her memory for some clue about her fate.

But time doesn't stand still, and the longer the search goes on, the higher its toll. The first casualty is Jake and Abby's relationship. Jake struggles not to blame Abby, but as much as he loves her, he can't help but wonder what would have happened to his daughter had he not let this new woman into their life. Abby, meanwhile, sees Jake changing into a man she doesn't recognize. The previously cynical, intellectual Jake, for example, finds solace in religion, urging Abby to attend services that leave her cold. Ultimately, he looks for closure. He decides Emma has drowned, despite evidence to the contrary, and holds a funeral service. Abby, meanwhile, keeps investigating, giving her life over to a quest that leads to a surprising conclusion.

Watching these characters, and those around them, deal with the trauma of unresolved grief, is fascinating. With a light touch, Richmond sketches even the minor characters in telling details. There's Nell, the neighbor who brings food when Abby isn't eating and then books as she begins to recover, and who gently encourages her to try hypnotherapy. There's David, the leader of the support group, whose own loneliness emerges and pushes him toward Abby, and there are other peripheral friends and family who are sympathetic, but unsure how to act as the crisis wears on.

Episodes from Abby's childhood pop up, underscoring the uncertainty of memory and also the tenuous nature of connection, but it's all done delicately, in almost poetic terms. Even the most obvious foreshadowing -- the dead seal pup, its "wet black eyes, open and staring" -- is simply mentioned, tossed up on the beach for us to consider, if we will.

It is a bit jarring, then, when Abby takes action, heading off to Costa Rica on an adventure that will ultimately answer her questions.

Although the author has set the stage for this phase of the book, both in terms of plot clues and Abby's increasing desperation, this last section loses some of the previous pages' poetry. Abby's adventure begins when she meets a surfer girl named Goofy who is also at a crossroads, and they encourage each other to take new chances. It's a natural transition, but after the static beauty of the first part of this book, it's a bit too much, too fast. How do we heal from such a horrible wound?

That's the underlying question in "The Year of Fog." Abby finds her way, but, like her, we can't help looking back with longing at all that has been lost.